APA (7th ed.) Citation

United States. Bureau of the Census. (1930). Classified index of occupations, 15th Census of U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Bureau of the Census. Classified Index of Occupations, 15th Census of U.S. [Washington]: GPO, 1930.

MLA (9th ed.) Citation

United States. Bureau of the Census. Classified Index of Occupations, 15th Census of U.S. GPO, 1930.

Warning: These citations may not always be 100% accurate.